Ballistic Phonon Thermal Transport in Multiwalled Carbon Nanotubes

Abstract

We report electrical transport experiments, using the phenomenon of electrical breakdown to perform thermometry, that probe the thermal properties of individual multiwalled carbon nanotubes. Our results show that nanotubes can readily conduct heat by ballistic phonon propagation. We determine the thermal conductance quantum, the ultimate limit to thermal conductance for a single phonon channel, and find good agreement with theoretical calculations. Moreover, our results suggest a breakdown mechanism of thermally activated C-C bond breaking coupled with the electrical stress of carrying 10 12 A=m 2 . We also demonstrate a current-driven self-heating technique to improve the conductance of nanotube devices dramatically.

Thermal resistance of the nanoscale constrictions between carbon nanotubes and solid substrates

“…[1][2][3] Of particular interest are carbon nanotubes, which have been proposed both as prototypical nanoscale circuit elements and by, virtue of their extraordinary current carrying capacity, as potential materials for interconnects. Recent studies have shown that nanotubes are remarkable thermal conductors [4][5][6][7][8] even at elevated temperatures 9,10 and ballistic phonon transport has been demonstrated in micron-scale devices, [11][12][13] with a mean free path in agreement to theoretical calculations. 14 Nevertheless, for thermal management it is also of interest to determine the thermal resistance between nanotubes and different materials.…”

“…However, these phonons are expected to decay into the thermal population before they can carry significant thermal energy out of the nanotube. 11 Figure voltages because of the increased scattering from optical or zone boundary phonon emission, tending towards the maximum of 4e / hE op-zb Ϸ 25 A/nanotube shell, where E op-zb ϳ 0.18 eV is the characteristic zone boundary or optical phonon energy in nanotubes. 21 Although the maximum current can vary for each device, the required power to reach breakdown increases approximately linearly with the nanotube length.…”

Electrical characteristics of multiwalled carbon nanotube arrays and influence of pressure

“…Similar results have also been observed for individual NTs. 4,11,13 The rapid increase of current with voltage has also been observed for experiments performed at different pressures (10 -6 Torr range) as shown in Figs. 2(b)-2(d).…”

“…9,10 Not only in the ballistic regime, but also the absence of current saturation has been reported in the diffusive regime. 4,[12][13][14] It may also be noted that IV characteristics reported in Refs. 6, 11 is different from that reported in Refs.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] The current-voltage (IV) characteristics of individual metallic NTs are shown to be dependent not only on diameter and length, [1][2][3][4][5][6][7][8][9][10][11][12] but also on the substrate-NTs interaction. 1 Remarkable is that the current saturation have been observed for metallic as well as semiconducting single-walled NT (SWNT), [1][2][3][4][5][6][7][8] which is attributed to the electron back scattering by high energy phonon, 3 and interband zener tunneling. 11 However, a series of independent transport measurements on various length demonstrated the absence of current saturation in NTs shorter than 55 nm.…”